Susceptible groups populations

B. Describe the populations that were assessed, including the general population, highly exposed groups and highly susceptible groups. 

Reference values indicate the upper margin of the current background exposure of the general population and [are used] to identify subjects with an increased level of exposure (Jakubowski and Trzcinka-Ochocka 2005) compared with the background population level. Those values are derived from data on blood, urine, and other tissues collected from population studies (Ewers et al. 1999). Reference values may be derived differently for susceptible groups if physiologic differences are substantial (for example, children vs adults) (Ewers et al. 1999). 

For prevention of disease in the elderly, the pregnant, or other susceptible groups, national fortification of food with vitamin B12 appears sensible and inexpensive but at present is not used and, in the absence of population screening s unlikely to be mandated by governmental edict. In general terms, the hematological manifestations of vitamin B12 deficiency are rapidly and fully correctable, although deficiencies of other micronutrients such as iron, folic acid, pyridoxine, copper, or vitamin C may be unmasked in the process and may limit the bone marrow s response until they are also corrected. 

Withers and Lees (1985) used lethality data from animal and human studies in a probit analysis to estimate concentrations that would be lethal to 50% (LC50) or to 10% (LC10) of a human population. They estimated a 30-min LC50 of 250 ppm for a normal population, 100 ppm for a susceptible population, and 210 ppm for the average population (combining normal and susceptible groups). The estimated LC10 for each population was 125 ppm, 50 ppm, and 80 ppm, respectively. 

Molecular toxicology has enabled toxicologists to understand events at the molecular level and examine alterations in fundamental biological processes that lead to the manifestation of toxic responses. As a result, toxicologists are examining the mechanisms of action of toxic substances in order to identify molecular changes predictive of exposure to harmful substances. This information can be used to identify susceptible groups within a population or establish... 

In fact, a beneficial effect on the emissions of NO has been attributed to MMT (Lynam etal. 1999). By contrast, several reports have shown that roadside air, soils, plants and animals are contaminated by elevated Mn concentrations (Thibault etal. 2002 Zayed etal. 1999). Consequently, Frumkin and Solomon (1997) concluded that especially susceptible groups of the population (fetuses, infants, children, pregnant and nursing women, the elderly people, individuals with pre-existing neurological... 

UI <100 iig/1) (Figure 48.2). Furthermore, there are a considerable number of countries, 24, in which the population may be at risk of increased susceptibility to iodine-induced hyperthyroidism in susceptible groups (median UI of 200—299 p.g/1), or at risk of adverse health consequences (median UI > 300 pg/l) (Andersson et al., 2005). 

The iodine intake is too high in 24 countries, and the population may be at risk of increased susceptibility to iodine-induced hyperthyroidism in susceptible groups or those at risk of adverse health consequences. 

Regular monitoring of iodi2ed salt quality and population iodine status is important to ensure that salt iodization is effective in the prevention and control of iodine deficiency, and that it does not expose susceptible groups to levels of iodine intake that are too high. 

The principal diagnostic labels assigned to this potentially susceptible group in the population by virtue of having chronic heart or lung disease would... 

Unusually susceptible populations are those groups of individuals who respond more quickly or at lower exposure levels than the general population to the toxic effects of methyl parathion. These responses may be genetic in origin or may be due to differences in development or life style factors such as nutrition or behavior, or due to preexisting disease states. 

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